The FACTDOUBLE function in Excel is used to compute the double factorial of a non-negative integer. The double factorial of a number is the product of all the integers from that number down to one, taking every second integer. This function is particularly useful in combinatorial calculations and advanced mathematical applications.

Syntax

FACTDOUBLE(number)

• number: A non-negative integer for which the double factorial is to be calculated.

Example #1

FACTDOUBLE(5)

Calculates the double factorial of 5, which is 5 × 3 × 1 = 15.

Example #2

FACTDOUBLE(6)

Calculates the double factorial of 6, which is 6 × 4 × 2 = 48.

Example #3

FACTDOUBLE(0)

Calculates the double factorial of 0, which is defined as 1, resulting in 1.

Error handling

• VALUE!: This error occurs if the input number is not a non-negative integer.
• NUM!: This message appears when the input number is negative, indicating that the double factorial cannot be calculated for negative numbers.

Conclusion

The FACTDOUBLE function is a powerful tool for anyone dealing with combinatorial mathematics or requiring precise calculations of double factorials. By understanding its parameters and proper usage, users can effectively apply this function to enhance their data analysis in Excel.